The Physics
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Opus in profectus

Matter Waves

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Problems

practice

  1. The Davisson-Germer experiment that first demonstrated the wave nature of matter used electrons accelerated to 54 V.
    1. Determine the energy of the electrons in…
      1. electron volts
      2. joules
    2. How fast were the electrons moving in this experiment?
    3. What momentum did these electrons have?
    4. Determine the wavelength of these electrons.
    5. What form of electromagnetic radiation has the same wavelength as the value you calculated in part d.?
  2. Repeat the Davisson-Germer experiment using a pitching machine that launches 145 g baseballs with a speed of 100 m/s at two doors separated by one meter. Determine…
    1. the momentum of the baseballs
    2. the de Broglie wavelength of the baseballs
    3. the distance in light years to the "screen" that would result in "bright" interference fringes separated by a distance greater than the diameter of one baseball (7.4 cm)
  3. As a first approximation, an electron in a hydrogen atom can be said to orbit the nucleus at a distance of 0.0529 nm. Determine the following quantities for an electron that just fits in the circumference of this orbit…
    1. its de Broglie wavelength in meters
    2. its momentum in kgm/s
    3. its kinetic energy in electronvolts
    4. its electric potential energy in electronvolts (watch the sign)
    5. its total energy in electronvolts
  4. Write something completely different.

conceptual

  1. Matter has both particle and wave properties.
    1. Why don't we notice the particle nature of matter in our everyday experience?
    2. What experimental evidence do we have to show that matter is composed of particles (atoms, molecules, ions)?
    3. Why don't we notice the wave nature of matter in our everyday experience?
    4. What experimental evidence do we have to show that elementary particles can behave like waves?
  2. Light and other forms of electromagnetic radiation have both particle and wave properties. Answer the following questions. Provide an example of a device, object, phenomena, or situation that can be used to demonstrate each of the two different models of light. Choose examples from common experience. No fancy laboratory experiments or abstract textbook situations.
    1. What evidence do we have that light is a wave?
    2. What evidence do we have that light is composed of particles (photons)?